ffmpeg decode raw h264

1. configure

configure --prefix=/usr/local/ffmpeg \
                       --enable-version3 \
                       --enable-gpl --enable-pthreads\
                       --disable-postproc --enable-avfilter \
                       --enable-shared \
                       --disable-ffserver --disable-ffplay \
                       --enable-encoder=rawvideo \
                       --enable-decoder=rawvideo \
                       --disable-encoder=asv1 --disable-encoder=asv2 \
                       --disable-encoder=bmp --disable-encoder=dvvideo \
                       --disable-encoder=ffv1 --disable-encoder=ffvhuff \
                       --disable-encoder=ppm --disable-encoder=rv10 \
                       --disable-encoder=targa --disable-encoder=xvid \
                       --disable-encoder=zlib

 2. compile

FFMPEG_ROOT=/usr/local/ffmpeg
FFMPEG_INC=${FFMPEG_ROOT}/include
FFMPEG_LIB=${FFMPEG_ROOT}/lib

gcc -o test.x test.c -I${FFMPEG_INC} -L${FFMPEG_LIB} -lavcodec -lavformat

 

 

3. ffmpeg decode raw h264 file to yuv (yuv420p)

 

#include <math.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <libavutil/opt.h>
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavutil/common.h>
#include <libavutil/imgutils.h>
#include <libavutil/mathematics.h>
#include <libavutil/samplefmt.h>

void usage(char *prog)
{
    fprintf(stderr, "Usage:\n");
    fprintf(stderr, "%s <ifile> <ofile>\n\n");
}

int main(int argc, char **argv)
{
    AVFormatContext *ic;
    AVCodec *dcodec, *ecodec;
    AVCodecContext *dec, *enc;
    enum AVCodecID codec_id;
    AVFrame  *avframe;
    AVPacket avpkt, pkt;
    int err, got_frame = 0, got_packet = 0, fd;
    char buffer[1<<16];

    if(argc < 3) {
        usage(argv[0]);
        exit(-1);
    }

    av_register_all();
    av_init_packet(&avpkt);
    av_init_packet(&pkt);
    pkt.data = NULL, pkt.size = 0;

    ic = avformat_alloc_context();
    if (!ic) {
        fprintf(stderr, "ic not created.\n");
        exit(-1);
    }

    err = avformat_open_input(&ic, argv[1], 0, 0);

    if(err < 0) {
        fprintf(stderr, "file [%s] not open.\n", argv[1]);
        exit(-1);
    }
 
    // dec = avcodec_alloc_context3(dcodec);
    dec = ic->streams[0]->codec;
    if (!dec) {
        fprintf(stderr, "Could not allocate video decoder context\n");
        exit(-1);
    }

    /* find the H264 video decoder */
    dcodec = avcodec_find_decoder(dec->codec_id);
    if (!dcodec) {
        fprintf(stderr, "dcodec not found\n");
        exit(-1);
    }

    /* open dcodec */
    if (avcodec_open2(dec, dcodec, NULL) < 0) {
        fprintf(stderr, "Could not open dcodec\n");
        exit(-1);
    }

    ic->probesize = (1<<20);
    avformat_find_stream_info(ic, NULL);

    /* reopen dcodec */
    if (avcodec_open2(dec, dcodec, NULL) < 0) {
        fprintf(stderr, "Could not open dcodec\n");
        exit(-1);
    }

    ecodec = avcodec_find_encoder(AV_CODEC_ID_RAWVIDEO);
    if (!ecodec) {
        fprintf(stderr, "ecodec not found\n");
        exit(-1);
    }

    enc = avcodec_alloc_context3(ecodec);
    if (!enc) {
        fprintf(stderr, "Could not allocate video encoder context\n");
        exit(-1);
    }

    enc->width = dec->width, enc->height = dec->height;
    enc->pix_fmt = dec->pix_fmt;

    // enc->codec_id = ecodec->id;
    // enc->codec = ecodec;

    if (avcodec_open2(enc, ecodec, NULL) < 0) {
        fprintf(stderr, "Could not open ecodec\n");
        exit(-1);
    }

    avframe = avcodec_alloc_frame();
    if(!avframe) {
        fprintf(stderr, "Could not allocate video frame\n");
        exit(-1);
    }

    fd = open(argv[2], O_CREAT|O_RDWR|O_TRUNC, 0666);

    while(av_read_frame(ic, &avpkt) >= 0) {
        got_frame = got_packet = 0;
        err = avcodec_decode_video2(dec, avframe, &got_frame, &avpkt);
        if(got_frame) {
            avcodec_encode_video2(enc, &pkt, avframe, &got_packet);
            write(fd, pkt.data, pkt.size);
            av_destruct_packet(&pkt);
        }
        av_init_packet(&avpkt);
    }

    fprintf(stderr, "finished.\n");

    // av_free(avframe);

    close(fd);
}

 

 

 

    dec->width = 720, dec->height = 480;
    dec->pix_fmt = AV_PIX_FMT_YUVJ420P;
    dec->pix_fmt = AV_PIX_FMT_YUV420P;

 

 

    enc->width = dec->width, enc->height = dec->height;
    enc->width = txtwidth, enc->height = txtheight;
    enc->pix_fmt = dec->pix_fmt;
    // enc->pix_fmt = AV_PIX_FMT_YUV420P;

    txtwidth = enc->width, txtheight = enc->height;